Field of the Invention
The present invention relates to a printing device, and particularly relates to a thermal transfer type of printing device.
Description of the Related Art
A technique is known for providing a protective layer (also referred to as an overcoat layer) on the outermost surface of printing paper for the purpose of protecting the printing surface or adjusting the glossiness of the printing surface. For example, Japanese Patent Laid-Open No. 2005-271321 proposes that in a thermal printer that uses printing paper provided with a transparent protective layer over a thermal color-forming layer, heat is applied to the protective layer using a thermal head after recording an image so as to change the glossiness of the protective layer in a regular manner, thereby giving a visual effect.
Japanese Patent Laid-Open No. 2005-271321 is based on the presumption that printing paper provided with a protective layer in advance is used, but there are apparatuses constituted to add a protective layer at the time of printing. Examples of such apparatuses include sublimation printers constituted to transfer a protective layer after printing with colors, inkjet printers for printing with transparent ink for smoothing the surface of paper, and the like.
In particular, in thermal transfer-type printers such as a sublimation printer, the surface texture of a protective layer after being transferred can be controlled by the heating pattern of the head when transferring the protective layer. For example, it is conceivable to improve the visual recognizability of a printed article by making the surface texture of the protective layer rough and suppressing reflection. However, depending on the heating pattern and the heat amount implemented in order to make the surface texture of the protective layer rough, the fusion strength between the protective layer and the resin film that supports the protective layer increases, and insufficient separation occurs, which prevents the protective layer from being transferred to printing paper.